1. Field of Invention
This invention relates to uses for inductive vehicle detection systems. More specifically, this invention describes a method for using a single-loop inductive sensor to estimate vehicular speed and length, and to communicate the speed and length information to a traffic controller.
2. Description of the Related Art
Numerous inductive vehicle detection systems have been installed in roadways around this nation. A conventional inductive vehicle detection system is a combination of wire-loop sensors, detector cards, and controller cards, which cooperate to obtain data on vehicles passing through the field of detection. Many of these inductive vehicle detection system installations use only a single wire-loop in any given traffic lane. In these conventional inductive vehicle detection systems, the amount of information available depends upon the configuration of the inductive vehicle detection system. Typically, obtaining a reliable measurement of vehicular speed requires two sequential wire-loops separated by a known fixed distance. Using arrival time and the distance between the wire-loop sensors, the vehicle speed is calculated. More recently, analysis methods have provided a way to estimate vehicular speed using data from a single wire-loop. However, in their present form, the single wire-loop vehicle speed analysis methods require a complete retrofitting of the detector cards and the controller card. The controller card is typically the most expensive component of the inductive vehicle detection system. There is a need to find a way to employ the single wire-loop vehicle speed analysis methods that makes better use of existing components of existing inductive vehicle detection systems, particularly the controller card.